Skip finalizer test if precise GC is not supported

[uweigand]

• Finalizer_OperationNotCompleted_CompletesOperation assumes precise GC

This test assumes the AsyncOperation object created in NotCompleted is collected by the GC.Collect() call. That is not guaranteed with the current Mono GC, which conservatively scans the whole stack. If a pointer to that object is still visible anywhere on that stack (or in any register, as the stack also contains register context save areas at the time GC.Collect() executes), the object may erroneously still be considered live.

Whether or not the test actually fails depends on accidental details of the generated code; the test used to pass on s390x but after some unrelated codegen changes (enabling the linears optimization in Mono), it now fails.

Simply make the test depend on IsPreciseGcSupported, like many similar tests already are.

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Issue Details

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• Finalizer_OperationNotCompleted_CompletesOperation assumes precise GC

This test assumes the AsyncOperation object created in NotCompleted is collected by the GC.Collect() call. That is not guaranteed with the current Mono GC, which conservatively scans the whole stack. If a pointer to that object is still visible anywhere on that stack (or in any register, as the stack also contains register context save areas at the time GC.Collect() executes), the object may erroneously still be considered live.

Whether or not the test actually fails depends on accidental details of the generated code; the test used to pass on s390x but after some unrelated codegen changes (enabling the linears optimization in Mono), it now fails.

Simply make the test depend on IsPreciseGcSupported, like many similar tests already are.

Author:	uweigand
Assignees:	-
Labels:	area-System.ComponentModel
Milestone:	-